MEZS7-PDCharger-MP2760 Reference Design

REFERENCE DESIGN

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Performance Summary ⁽¹⁾

Specifications are at T_A = 25°C, unless otherwise noted.

1) Refer to the MP2760 datasheet for more details.

2) These items can be configured by the MPF52002 via the I²C interface.

3) These items are configured by the MPF52002 automatically, according to the protocol.

Evaluation Board

LxWxH (6cmx5cmx2.1cm)

Table 1: Battery Cell Number and V_{SYS_MIN} Setting ⁽⁴⁾

4) Set PB2 and PB3 to configure the cell number and V_{SYS_MIN} before charging a real battery.

Quick Start Guide

The MEZS7-PDCharger-MP2760 is a 2-cell to 4-cell series power delivery (PD) charger module using the MP2760 and MPF52002. It is a reference design for PD applications and includes a DRP USB Type-C port. The charge current is preset to 3A, and the charge-full voltage is preset to 8.4V for a 2-cell series Li-ion battery. In reverse source mode, the output is preset to 5V/3A or 27W PD. All the charging/discharging parameters are set by the MPF52002.

The user can download their own charge parameter settings to the MPF52002’s volatile memory via the I²C after start-up. The user can also download these parameters to the MPF52002’s non-volatile memory (NVM), which is not reset until even if the part completely powers off.

Follow the steps below to prepare the battery and load connection for testing:

1. Connect the series battery terminals to:
1. Positive (+): VBATT
2. Negative (-): GND

If using a battery simulator, preset the battery voltage, then turn it off. Connect the battery simulator output terminals to:

1. Positive (+): VBATT
2. Negative (-): GND
2. Ensure that the battery voltage is present (if using a battery simulator, keep the simulator on).
3. Connect the system load terminals to:
1. Positive (+): SYS
2. Negative (-): GND

Before adapter plug-in, ensure that the PB2 and PB3 settings are correct (see Table 1). Otherwise, the system load and battery may be damaged.

Sink Mode

Connect the USB Type-C port to an adapter with a USB Type-C to Type-C or Type-A to Type-C cable. MP2760’s I_{IN_LIM} and adapter’s output voltage is set according to the negotiation result between the adapter and board, and then charger operation starts.

The default firmware of the MPF52002 on this evaluation board supports the following protocols in sink mode:

• PD3.1
• For a non-PD adapter, the bus voltage (V_BUS) is 5V. The default input current (I_IN) limit is 900mA. If there is a Rp on source CC termination, then I_{IN_LIM} can rise to 1.5A or 3A, according to the Rp value.

The MPF52002 automatically requests the maximum input power, according to the adapter’s protocol.

The MPF52002 sends an I²C command to the MP2760, and then MP2760 charges the battery. For 2-cell applications, the default minimum system voltage (V_{SYS_MIN}) is 6.2V, and the default battery-full regulation voltage is 8.4V. The CC charge current limit is set to 3A by default.

If the input power is sufficiently high, the charge current is 3A by default. The real charge current may be limited by the input power limit if the input power is not sufficiently high. If the maximum adapter power is below the maximum charging power rating, the input current limit loop adjusts the charge current to avoid overloading the source/adapter.

Figure 1 shows the set-up for sink mode.

Figure 1: Sink Mode Set-Up

Source Mode

Connect the devices to the USB Type-C port with a USB Type-C to Type-C, Type-C to micro-B, or Type-C to lighting cable. Source mode can start automatically and provide the proper voltage to devices as requested.

The default firmware for the MPF52002 on this evaluation board supports the following protocols in source mode:

• PD3.1
• DCP
• Apple mode

VBUS should start up automatically at the default voltage set by the PD protocol sniffer or mobile device. The PD protocol sniffer can select different PDO outputs.

The default PD output power is 27W.The battery discharge current limit is 6.4A.

Figure 2 shows the set-up for source mode.

Figure 2: Source Mode Set-Up

I²C Target Function Description

The MP2760 and MPF52002 can be controlled or monitored via the I²C between the MPF52002 and I²C initiator (see Figure 3). The initiator should be connected to the MPF52002 through the I²C (PB6 and PB7) instead of the MP2760. The MPF52002 periodically reads the MP2760’s charge parameters and alert status, then updates the information to the I²C target registers. The initiator can also send certain I²C commands to the MP2760 through the MPF52002.

Figure 3: MPF52002 I²C Target Diagram Block

Hardware Set-Up for I²C Connection

The MPF52002 enters a deep sleep status to save power when the device is only using a battery, and I²C target is disabled. Before starting I²C communication, there are two methods to make the MPF52002 and I²C target function wake up, described below.

• Short PB1 (INT pin in CN3) to GND in battery-only mode.
• A USB Type-C device or adapter is connected to the USB Type-C port.

After communication wakes up, connect the PC and evaluation board with dongle(the EVKT-USBI2C-02 communication interface). The I²C’s SCL should be connected on PB6, which has a SWDIO silkscreen print. The I²C’s SDA should be connected on PB7, which has a SWCLK silkscreen print (see Figure 4).

Figure 4: Hardware Connection for I²C Communication

Time Requirements for the I²C Initiator

• The initiator SCL clock frequency is 400kHz (fast mode), compliant with a 100kHz to 400kHz clock.
• Read or write 1 byte in every command. Does not support reading/writing multiple bytes.
• A 10ms (or longer) delay between two I²C commands is recommended.

Evaluation Board Schematic

Figure 5: Evaluation Board Schematic

Solution Module Test Results

Performance curves and waveforms are tested on the evaluation board. The input power source is a PD adapter, V_IN = 20V, V_BATT = 8V, T_A = 25°C, default register data, unless otherwise noted.